It has long been recognized that the development of body malodours is at least partly due to bacterial action on the products of the sweat glands. Washing with a detergent, for instance in the form of a personal washing bar such as a soap bar, removes malodorous products and reduces the concentration of bacteria on the skin. Complete elimination of bacteria cannot usually be achieved by this means and for this reason it has also been customary to incorporate germicides into detergent compositions for personal washing in the belief that growth of those skin microflora that contribute to body malodour can be inhibited and the production of malodorous substances suppressed by them. Such germicides are at least partly effective in reducing or retarding the development of body malodour, but they do not completely solve the problem, possibly because there are other causes of malodour development on the skin which are unrelated to the proliferation of bacteria.
The limited effectiveness of germicides as the sole deodorant agent in a soap bar in combating the problem of body malodour can be demonstrated by determining the reduction in the intensity of body malodour obtained when standard soap bars containing different levels of germicide are compared by a test based on that devised by Whitehouse and Carter as published in The Proceedings of the Scientific Section of the Toilet Goods Association, Number 48, December 1967 at pages 31-37 under the title "Evaluation of Deodorant Toilet Bars". Details as to how this test is conducted are given later in this specification under the heading "Odour Reduction Value Test" but it can be stated now that when this modified test is employed using, for example the germicide 3,4,4'-trichlorocarbanilide instead of deodorant perfume, it has been possible to demonstrate that the maximum reduction in odour intensity obtainable (i.e. the numerical difference between the scores attributed to the test soap bar with germicide and the control soap bar without germicide, hereinafter referred to as the odour reduction value) is not greater than about 0.4, irrespective of the amount of the germicide in the test soap bar.
Typical results are summarised in the following Table.
TABLE 1 ______________________________________ The effect of 3,3,4'-trichloro-carbanilide on the reduction of odour intensity when tested against control soap bars containing no germicide Wt % germicide in soap bar Odour Reduction Value ______________________________________ 0.16 0.10 0.25 0.14 0.5 0.22 0.75 0.27 1.0 0.30 2.0 0.37 ______________________________________
Similar results are obtained if a mixture of two or more germicides, for example 3,4,4'-trichloro-carbanilide and 3,5,4'-tribromo-salicylanilide, are tested in the same way: the maximum odour reduction value obtainable is still only about 0.4.
Perfumes have been used as odour maskants since ancient times, and it is customary to incorporate perfumes into detergent compositions for personal washing such as soap bars, though these perfumes are in general ineffective in preventing the development of malodour.
In Brazilian Patent Application No. PI 7604601 published Aug. 16, 1977, perfumes having deodorant properties are described. These perfumes can be incorporated into detergent compositions such as soap which when applied to human skin can reduce body malodour. The materials contained within these perfumes which are collectively responsible for their deodorant property can be identified as satisfying either or both of two tests known respectively as the Lipoxidase Test and the Morpholine Test. The conduct of these Tests is fully described in the specification of the Brazilian patent application and is reproduced in full herewith for the sake of completeness.
It has now been discovered that certain combinations of perfume materials, hereinafter referred to as deodorant perfumes, when incorporated into detergent compositions containing a conventional germicide for personal washing provide a more effective means for inhibiting malodour development than the use of such a germicide alone, in that the odour reduction value, as measured according to the Odour Reduction Value Test, can exceed 0.4. This effect is clearly not solely one of odour masking, since in many instances there is no detectable smell of the perfume on the treated skin after a few hours. Accordingly, the use of deodorant perfumes and germicides in deodorant compositions represents a new operative principle.
In the course of attempts to characterise this new principle, many hundreds of known perfume materials have been screened. Hundreds of formulations made by blending materials have been examined, including a number of commercial perfumes whose formulations are not fully known (being confidential to the perfumery house in question offering the perfume for sale). No commercial perfume has been found that is capable of giving a germicide-containing soap bar the malodour-inhibiting property attributable to a mixture of germicide and deodorant perfume. This supports the view that a new principle of an entirely unexpected kind has been discovered.